Tool-less blade clamping apparatus for a reciprocating tool

ABSTRACT

Several preferred embodiments are disclosed for a tool-less blade clamping apparatus for a reciprocating tool of the type which has a reciprocating plunger which has a tool attachment receiving slot for receiving a tool attachment of the type that has a shank portion. The clamping apparatus has an unclamped position and a clamped position. In the unclamped position, a tool attachment can be easily inserted and when it is in its clamped position, the tool attachment is securely retained. The preferred embodiments have at least one spring biasing the apparatus toward the clamped position, a releasable retaining mechanism for holding the apparatus in its unclamped position after being placed in that position. When the blade shank portion is inserted into the slot a predetermined distance, the shoulders of the shank portion release the retaining mechanism to move it to its clamped position. When a blade is to be removed, the clamping apparatus needs only to be moved to its unclamped position by manually rotating the outer sleeve or collar, and the blade is normally ejected from the mechanism by contact with the blade shoulders as it reaches its unclamped position.

This application is a continuation of application Ser. No. 12/961,772,filed on Dec. 7, 2010 (now U.S. Pat. No. 8,393,625), which in turn is acontinuation of application Ser. No. 10/760,110, filed on Jan. 16, 2004(now U.S. Pat. No. 7,871,080). The disclosures of the twoabove-identified patent applications are hereby totally incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION

The present invention generally relates to tools. More particularly, itrelates to mechanisms for clamping tool attachments to such tools.

While reciprocating tools such as jigsaws, saber saws and otherreciprocating tools, including medical and surgical instruments, havebeen used for decades, the mechanisms for attaching a tool attachment tothe reciprocating portion has evolved from various attachment mechanismsthat required separate tools of one kind or another, typicallyscrewdrivers, wrenches or levers, to attach the tool attachment to areciprocating member by tightening screws or the like. Because suchattachment mechanisms are often located in a confined space in the tool,it is often inconvenient to attach or remove the tool attachment, whichcan comprise a cutting blade, a saw blade, an abrasive, polishing orsmoothing member or the like from the tool. Moreover, since specialtools were often required, it was necessary to have such tools availableduring use in the event the tool attachment breaks or otherwise needs tobe changed because it is worn out or a different type of tool attachmentis needed.

There has been a concerted effort in recent times to develop new kindsof attachment or clamping mechanisms that do not require the use oftools to mount and remove tool attachments from the tool. Whilemechanisms are known in the prior art that have this capability, thevarious known designs have varying degrees of effectiveness in securelyholding the tool attachment in the tool, or in the ease and convenienceof operation in mounting or removing tool attachments from the tool orin the degree of complexity and therefore cost of manufacture.

It is a continuing goal of designers to develop clamping mechanisms forsuch reciprocating tools which have superior design features, areeffective to provide the desired amount of force to clamp the toolattachment, are easily operated, and have a minimum number of parts thatare easily manufactured and assembled to thereby minimize the cost ofmanufacture.

SUMMARY OF THE INVENTION

Several preferred embodiments of the present invention are disclosedherein for a tool-less blade clamping apparatus for a reciprocating toolof the type which has a reciprocating plunger which has a toolattachment receiving slot for receiving a tool attachment of the typethat has a shank portion with at least one, and preferably two shouldersspaced from the end of the shank and an aperture in the shank forfacilitating holding by the clamping apparatus. In all of the disclosedpreferred embodiments shown and described herein, the clamping apparatushas an unclamped position and a clamped position where the shank portionof the tool attachment can be inserted into the slot as well as anopening in the apparatus itself. In the unclamped position, a toolattachment can be easily inserted and the shoulders will release theapparatus to move to the clamped position, where the tool attachment issecurely retained. When returned to the unclamped position, theapparatus engages the shoulders and pushes the blade from the apparatus.

The preferred embodiments have at least one spring biasing the apparatustoward the clamped position, a releasable retaining mechanism forholding said apparatus in its unclamped position after being placed inthat position, such that when the retaining mechanism is releasedresponsive to the blade shank portion being inserted into the openingand slot and the shoulders engage the apparatus and is thereafter moveda predetermined distance, the retaining mechanism is released to move toits clamped position. When a blade is to be removed, the clampingapparatus needs only to be moved to its unclamped position by manuallyrotating the outer sleeve or collar, and the apparatus pushes againstthe shoulders of the blade which causes the blade to normally be ejectedfrom the mechanism as it reaches its unclamped position.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the first preferred embodiment of theclamping apparatus shown with a blade inserted in the apparatus in itsclamped position;

FIG. 2 is an exploded perspective illustrating the components of theapparatus shown in FIG. 1;

FIG. 3 is an enlarged perspective view illustrating a portion of theapparatus shown in FIG. 1;

FIG. 4 is a cross-section taken generally along a line perpendicular tothe orientation of the slot of the plunger rod at a location through thecenter of the detente;

FIG. 5 is a perspective view with portions removed to illustrate many ofthe components of the apparatus shown in FIG. 1;

FIG. 6 is a perspective view of the inner sleeve of the apparatus shownin FIG. 1;

FIG. 7 is another perspective view of the inner sleeve shown in theapparatus of FIG. 1;

FIG. 8 is a perspective view of the outer sleeve of the apparatus shownin FIG. 1;

FIG. 9 is another perspective view showing the interior of the outersleeve of the apparatus shown in FIG. 1;

FIG. 10 is a perspective view of the detente used in the apparatus shownin FIG. 1;

FIG. 11 is a perspective view of a second preferred embodiment of aclamping apparatus;

FIG. 12 is an exploded perspective illustrating the components of theapparatus shown in FIG. 11;

FIG. 13 is a perspective view of the apparatus shown in FIG. 11 shown incross-section taken generally through the center of the apparatus alonga plane parallel to the slot of the plunger rod;

FIG. 14 is a perspective view of the apparatus shown in FIG. 11 withportions removed to illustrate the relationship of components thereof;

FIG. 15 is a perspective view with portions removed to reveal across-section taken generally along a plane transverse to the axis ofthe apparatus and through the center of the detente;

FIG. 16 is a perspective view of a third preferred embodiment of theclamping mechanism;

FIG. 17 is an exploded perspective view of the apparatus shown in FIG.16;

FIG. 18 is a perspective view of the apparatus shown in FIG. 1 withportions removed to illustrate the relationship of components of theapparatus shown in FIG. 16;

FIG. 19 is a cross-section with portions removed to illustrate across-section taken along a plane generally transverse to the axis ofthe apparatus and taken at a position to reveal the middle of thedetente;

FIG. 20 is a perspective view of the clamping collar of the apparatusshown in FIG. 16;

FIG. 21 is a perspective view of the control sleeve of the apparatusshown in FIG. 16; and

FIG. 22 is a perspective is another perspective view of the clampingcollar of the apparatus shown in FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the various embodiments of the present invention can be used withvarious power hand tools jig saws, saber saws and other reciprocatingsaws used in the construction and woodworking applications, it should beunderstood that the clamping apparatus is certainly susceptible for usein applications other than these. It is contemplated that the clampingapparatus may be used in the medical field, particular with surgicalinstruments that are used with reciprocal saw and cutting blades. Also,while the embodiments of the present invention are particularly suitedfor use with power hand tools, they could be used with a nonpower handtool as well as larger stationary power tools that employ toolattachments in a reciprocating manner and where such tool attachmentsare replaced. The detailed description of the preferred embodiments aredescribed with regard to saber saws which use commercially available sawblades. The present invention should not be limited to the describedapplications.

The embodiments of the clamping apparatus of the present invention areparticularly suited for use with a saber saw which has a generallycylindrical plunger rod although plunger rods or structure may beutilized which are other than the circular cross-section. However, if itis other than a circular cross-section throughout a significant part ofits length, the plunger rod necessarily requires a generally cylindricaldistal end portion in which the embodiments of the present invention areinstalled. The blade described herein in which the clamping mechanism ofthe embodiments of the present invention are to be used is ofconventional design for saber saw blades, but it should be understoodthat the various embodiments could be modified to operate with otherstyles of blades if desired. The modification should be such that a holebe located somewhere on the shank portion of the blade and the bladeshould have at least one shoulder of the type described herein forreleasing the apparatus from an unclamped position to a clampedposition, and for ejecting the blade from the apparatus.

There are three preferred embodiments shown and described herein, withthe first embodiment being illustrated in FIGS. 1 through 10, the secondembodiment in FIGS. 11 through 15 and the third embodiment in FIGS. 16through 22. A feature common to all embodiments is the aspect that theblade has at least one shoulder, and preferably two shoulders onopposite sides of the blade for engaging the apparatus during insertionof the blade in the apparatus. The shoulders contact the apparatus andrelease it which causes it to move to a clamped position. When it isdesired to remove the blade, the apparatus is manually returned to itsunclamped position and when it reaches that position the apparatusengages the shoulders and normally ejects the blade from the apparatus.This type of functionality is different from other prior art bladeclamping mechanisms which utilize the end of the shank to cause theapparatus to move to the clamped position and also contact the end ofthe shank to remove it from the mechanism. The preferred embodiments ofthe present invention have an important advantage over this prior artmechanism in that the preferred embodiment can function with bladeshaving shank portions of varying lengths. The insertion and ejection ofthe blade is achieved as a result of the shoulders in the shank portionof the blade and not the end of the shank.

With regard to the first preferred embodiment, the blade clampingapparatus is shown generally at 10 attached to a plunger rod 12 that istypically a part of a reciprocating power tool such as a saber saw orother reciprocating tool that is designed to use a removable orreplaceable tool such as a cutting blade, saw blade or the like that ismounted to a plunger rod wherein the plunger rod has a reciprocatingaction. The clamping apparatus 10 is shown in FIG. 1 with a blade 14clamped in place. The apparatus 10 is installed on the plunger rod 12that extends to a reduced diameter end portion 16 which has a slot 18(see FIG. 2), through which a shank portion 20 of the blade 14 isinserted.

With regard to the shape of the blade 14 described herein, which is agenerally typical shape and is commercially available from manymanufacturers, it has a shank 20 that is generally of the same thicknessas the blade portion 14 but is narrower than the blade portion in thatthe transition from the shank portion to the blade portion creates ashoulder 22 on each side of the blade. The end 24 of the blade 14 mayhave a notch 26 and the shank preferably has a hole 28 located in itcenter generally midway between the end 24 and the shoulder 22 in thelongitudinal direction of the blade, all of which is shown in FIG. 5.

As shown in FIGS. 1-10, the apparatus 10 has an outer sleeve, indicatedgenerally at 30, which has a generally hollow cylindrical configurationwith a reduced diameter end wall 32 that has an opening 34 that is sizedslightly larger than the diameter of the end portion 16 of the plungerrod 12 and also slightly larger than the width of the shank portion 20of the blade 14 so that the shank portion can be inserted into the slot18 of the rod end portion 16 and the opening 34. The outer sleeve 30 hasa thickened portion 36 that has a generally square shape and increasesfrom a relatively small thickness at end 38 and to a thicker portion atthe opposite end 40, with a transverse end wall 42 providing a grippingsurface for a user to more easily rotate the outer sleeve 30 in thecounterclockwise direction indicated by the arrow 44 to place theapparatus in an unclamped position. A second thickened portion 46 isprovided diametrically opposite the portion 36 for enablingsymmetrically balanced gripping by a user.

The outer sleeve 30 has a circumferential elongated slot 48 with atransverse axially aligned extension 50 at one end thereof in which aforward pin 52 is preferably press fit into an opening 54 in the end 16of the plunger rod 12. A diagonal wall 56 is defined by a recess in theinside of the outer sleeve, i.e., the left end portion 58 of the recessas shown in FIGS. 1 and 2 is closer to the front end wall 32 than theright end 60 of the recess. The wall 56 has a length that isapproximately equal to the length of the slot 48 in that rotation of thepin 52 in the slot 48 extends through an arc that is preferably at leastequal to the angular arc between ends 58 and 60 of the wall 56.

The apparatus also includes an inner sleeve, indicated generally at 70,which also has a hollow cylindrical configuration and an outer diameterthat is sized to closely fit within the outer sleeve 30 and which has aninner diameter that is slightly larger than the outside diameter of theplunger rod end portion 16 on which it slides. The inner sleeve has apair of protrusions 72 that are diametrically opposite one another andan axial recess 74 that extends from the front end rearwardly toward theupper protrusion 72. The width of the recess is approximately equal tothe diameter of the pin 52 and the axial length of the recess 74 isapproximately equal to the axial distance between the ends 58 and 60 ofthe groove 56. In this way, the inner sleeve 70 can move in the axialdistance by an amount equal to the axial distance between ends 58 and60, but is restrained from rotation by virtue of the pin 52 riding inthe recess 74.

While not specifically illustrated, the outer sleeve 30 has a recessdiametrically opposed to the recess defining the wall 56 that isvirtually identical to it, but diametrically opposed. The protrusion 72is adapted to fit within the recess defining the wall 56 and theopposite protrusion similarly engages the recess slot on the oppositeside of the outer sleeve 30, so that when there is relative rotationalmovement between the inner sleeve and the outer sleeve, the angularorientation of the slot 48 will cause axial movement of the inner sleeve70 relative to the outer sleeve 72. As is best shown in FIG. 7, theinner sleeve 70 also has a pair of radially oriented inwardly extendingribs 76 that are diametrically opposite one another that are configuredto fit within the slot 18 of the end portion 16 of the plunger rod 12which prevents rotational movement of the inner sleeve 70 relative tothe outer sleeve or the plunger rod 12.

The apparatus also includes a compression spring 78 which bears againstthe inner sleeve 70 and against a spring retainer 80. The spring 78 hasan inside diameter that is slightly larger than the end portion 16 ofthe plunger rod so that it fits over the same. The spring retainer 80has an inside diameter that is only slightly larger than the outsidediameter of the end portion 16 and slides on it until it reaches anannular shoulder 82 that is formed by the end portion 16 being of aslightly smaller diameter than the main portion of the cylindricalplunger rod 12. A detente 84 is provided which fits into an opening 85on the bottom side of the end portion 16 below the slot 18. The detente84 has a conical upper end portion 86 and a bottom end 88 that may be ofa hemispherical shape or at least slightly curved.

As best shown in FIGS. 4 and 6, the inner sleeve 70 has an inclined orramped surface 90 that is formed in the front end of its top portionwhich is configured to engage the detente 84 when the apparatus is inits clamped position, i.e., when the inner sleeve 70 is at its mostforward position relative to the outer sleeve 30. This occurs when theprotrusion 72 is at the left end 58 as shown in FIG. 1. In thisposition, the inclined ramp surface 90 bears against the detente 84 andpresses the conical portion 86 thereof into the opening 28 of the blade14 to thereby firmly clamp the blade 14 so that it cannot be easilyremoved.

During operation of this embodiment, when a blade 14 is to be insertedinto the apparatus, the apparatus is in its unclamped position which isdifferent from the clamped position shown in FIG. 1 in that the outersleeve 70 is rotated in the counterclockwise direction of the arrow 44so that the pin 52 is at the opposite end or left end of the slot 48 asshown in FIG. 1. Because of the biasing force of the compression spring78 against the inner sleeve 70, when the pin 52 is at the right end ofthe slot 48, the force of the spring will cause the inner sleeve to bemoved forwardly or left in FIG. 1 which in turn causes the outer sleeve30 to be moved relative to the pin so that it engages the transverseextension 50. When it reaches that point, it is in the unclampedposition and it will be retained in this position until a blade isinserted into the apparatus.

To insert and clamp a blade, it is inserted into the slot 18 and opening34 until the shoulders 22 engage the end 32 of the outer sleeve 30 atwhich point further inward force causes the outer sleeve to be movedrearwardly or right as shown in FIG. 1 so that the pin 52 will bealigned with the slot 48 and the force of the spring 78 will cause theprotrusion 72, which at that point and time will be located on theopposite end 60 of the diagonal wall 56 and cause it to rotate the outersleeve 30 relative to the inner sleeve 70 and thereby move it to theposition as shown in FIG. 1. During that movement, the inner sleeve 70will also move to the left or forwardly in the apparatus and cause theinclined surface 90 to engage the detent 84 and engage the hole 28 inthe blade 14 to firmly secure it.

If the blade is to be subsequently removed, a user will grip the outersleeve and rotate it counterclockwise in the direction of the arrow 44.When it reaches the position where the pin 52 is in line with thetransverse extension 50, it will be quickly moved to the left which willeject the blade 14 from the apparatus.

The second preferred embodiment is similar in principle to the first inthat it has an unclamped and clamped position and the apparatus isnormally in an unclamped position when no blade is inserted in it andupon insertion of a blade a predetermined distance, it is released tomove toward the clamped position. Similarly, when it is manually rotatedtoward the unclamped position, it will eject the blade when itapproaches the unclamped position. Rather than moving an inclinedsurface in an axial direction to move the detente into the aperture inthe shank of the blade 14, this preferred embodiment has a ramped or camsurface that engages the detente as a result of rotation of a clampingcollar.

Turning now to the drawings, and referring to FIGS. 11-15, the clampingapparatus is indicated generally at 100 and is mounted on a plunger rodend portion 16 that is substantially similar to the rod end portion 16of the first preferred embodiment. It also has a slot 18 as well as aflange 82 that is formed as a result of the diameter of the end portion16 being less than the diameter of the main portion of the rod 12. Theapparatus 100 has a generally cylindrically shaped hollow controlsleeve, indicated generally at 102, that has a forward end portion 104and an opening 106 that is slightly larger than the outer diameter ofthe end portion 16. The plunger rod also has an opening 54 in which apin 108 is inserted and which extends outwardly so as to ride in acircumferential elongated slot 110 that has a transverse extension 112that is directed rearwardly. The configuration of the slots 110 and theextension 112 is substantially similar to the slot and extension 48 and50 of the first preferred embodiment.

A clamping collar 124 has a generally hollow cylindrical configurationwith the outside diameter being slightly smaller than the insidediameter of the control sleeve 102 so that it fits within it. The insidesurface of the clamping collar 124 is generally cylindrical in shape buthas a portion 126 that has an arc of approximately 90° that increases inits radial distance from the center of the clamping collar beginning atlocation 128 shown in FIG. 15 and increasing to point 130 which definesa cam surface 132. The clamping collar 124 has an axial groove in itsoutside surface 134 configured to receive an axial rib 136 that isformed on the inside of the control sleeve 102. This interlocking riband groove configuration causes the control sleeve 102 and clampingcollar 124 to rotate together during operation of the apparatus 100.

The clamping collar also has an aperture 137 that extends substantiallythe full length of the clamping collar and is sized to receive atransverse end leg 138 of a torsion spring 140. An opposite leg 142 isoriented in a radial direction in the center of the spring so that itfits within the slot 18 of the plunger end portion 16. This secures theend portion 142 from rotation so that the opposite end portion 138 wheninserted into the aperture 136 creates a torsional force applied to theclamping collar 124 and the control sleeve 102 if they are rotatedrelative to the position of the end 142.

A generally cylindrical support ring 144 has a reduced diameter forwardportion 146 that defines an annular shoulder 148 that is sized to engagethe rear end surface of the control sleeve 102. The support ring 144also has a rearward extension 152 (see FIGS. 13 and 14) that fits on theend portion 16 of the plunger rod 12. A compression spring 154 bearsagainst the support ring 144 as well as against a generally cup-shapedspring retainer 156. The inside diameter of the rear end of the springretainer is sized to closely fit the diameter of the end portion 16 andit contacts and is held by the annular shoulder 82 of the plunger rod12. A detente 158 is provided and fits into an aperture 160 (see FIGS.14 and 15) in the end portion 16 of the plunger rod. In this embodiment,the axial position of the aperture 160 and the aperture 54 are differentas readily shown in FIG. 14. A smaller circular recess 162 is preferableground into the face of the slot 18 adjacent to the conical portion ofthe detente 158 to assure that the detente 158 will firmly engage theblade 14 when it is inserted into the apparatus. As in the firstembodiment, the detente 158 engages the opening 28 of the blade shank20.

During operation of this embodiment, when the apparatus 100 is in itsunlocked position and referring to FIG. 11 (which shows the apparatus ineither its clamped or unclamped position), the pin 108 will be locatedin the slot the extension 112. This holds the apparatus in thisunclamped position. When a blade 14 is inserted into the apparatus, theshoulders 22 of the blade will engage the front end wall 104 of thecontrol sleeve 102 and with sufficient force applied will move thecontrol sleeve 102 in the rearward direction which will release the pin108 from the slot extension 112 and biasing force resulting from thetorsion spring 140 will rotate the control sleeve 102 as well as theclamping collar 124 in the clockwise direction as shown by arrow 164.Clockwise rotation of these two components enables the cam surface 132of the clamping collar 124 to engage the detente 158 and move itradially inwardly to engage the hole 28 in the shank 20. When the blademoves the control sleeve 102 rearwardly, it compressed the compressionspring 154 by engaging the support ring 144 and pushing it in therearward direction.

To unlock the apparatus, a user manually rotates the control sleeve 102in the counterclockwise direction, i.e., the direction opposite thearrow 164, which causes the cam surface 132 to release the detente 158and when the rotation is sufficient so that the pin 108 is axiallyaligned with the transverse extension 112, the compression spring willforce the spring support and control sleeve forwardly which causes thepin to enter the transverse slot 112 which is the unclamped position ofthe apparatus. The movement of the control sleeve 102 forwardly normallyejects the blade as a result of the front end wall 104 pushing the bladefrom the slot 18.

With regard to the third embodiment and referring to FIGS. 16-22, it issimilar to the embodiment shown in FIGS. 11-15 in that the apparatus 200has a cam surface that also engages a detente by rotation thereof. Theassembled apparatus is indicated generally at 200 and is shown to beinstalled on a plunger rod 12 having a slightly reduced diameter endportion 16 which thereby forms the shoulder 82 as shown with regard tothe prior described embodiments. The end portion 16 has a slot 18 forreceiving the blade 14 which has the same configuration as has beendescribed with regard to the first and second preferred embodiments. Theapparatus 200 has a clamping collar, indicated generally at 202, thathas an elongated slot 204 in which a pin 206 which is preferably forcefit in an aperture 208 in the upper side of the end portion 16. Becausethe pin is secured in the plunger rod end portion 16 and the diameter ofthe pin is comparable to the width of the slot 204, the only movementthat is permitted by the clamping collar 202 is rotational movement.

The clamping collar 202 has a radially inwardly directed protrusion 210located at the front end thereof that is relatively thin and narrow asshown in FIG. 20. The clamping collar 202 also has plurality of smallramp-like protrusions 212 as well as two larger protrusions 214 whichfacilitate gripping by a user to rotate the clamping collar to theunclamped position as will be hereinafter explained. The clamping collaralso has an axial rib 211 in the rear portion thereof for engaging arecess in a support ring 218. The rear part of the support ring 218 hasan enlarged end forming a shoulder 224 that is adapted to contact theend surface of the clamping collar 202. The main part of the supportring 218 is adapted to slide within the rear portion of the clampingcollar 202. By virtue of the complementary rib and recess construction,the support ring 218 and clamping collar 202 will necessarily rotatetogether as is desired. The support ring 218 also has an axiallyoriented aperture or slot 226 that is adapted to receive the transverseend 228 of a torsion spring 230, the opposite end thereof being radiallyoriented and configured to fit within the slot 18 of the plunger rod end16.

A generally hollow cylindrical control sleeve 234 fits around theplunger end portion 16 and inside of the clapping collar 202. Thecontrol sleeve 234 has an annular groove 236 near the front portion 236located near its front and the annular groove 236 merges with aperpendicular axially oriented groove 238 that extends from the annulargroove 236 to the rear end of the control sleeve 234. The control sleeve234 also has a flared front 240, the inside surface of which isgenerally configured to conform with the shape of shoulders of manycommercially available blades 14. The control sleeve 234 also has anelongated opening 242 through which the pin 206 passes. This enables thecontrol sleeve 234 to move in the axial direction, but is precluded fromrotating relative to the plunger rod end portion 16.

A compression spring 244 is located inside of the clamping collar 202and has a diameter that is approximately equal to that of the controlsleeve 234 so that the front end of the spring 244 bears against therear surface of the control sleeve 234 when the apparatus is assembled.The spring 244 has a diameter that is only slightly larger than thediameter of the end portion 16, and the rear end of the spring 244 bearsagainst a spring retainer 246. The spring retainer 246 has an internaldiameter that is only slightly larger than the diameter of the endportion 16 but smaller than the diameter of the main part of the plungerrod 12 so that it is restrained by the shoulder 82 of the plunger rod. Adetente 248 fits within the aperture 250 in the end portion 16 of theplunger rod 12. The detente 248 also has a conical configuration at theend which engages the blade 14 and a curved opposite end portion.

The detente 248 is moved toward and away from the blade 14 duringoperation by virtue of a cam surface 252 that is shown in FIG. 19 andwhich extends from approximately location 254 to location 256, with thelocation 256 having a larger radius from the center of the apparatusthan the location 254. In this regard, it is similar to the cam surfaceof the second embodiment.

During operation of this embodiment, when a blade 14 is inserted intothe slot 18 with the apparatus 200 in its unclamped position, theprotrusion 210 of the clamping collar 202 is located in the axial slot238 of the control sleeve 234. When the blade is pressed into theapparatus with sufficient force to travel a predetermined distance, thecontrol sleeve 234 is moved axially in the reverse direction until theprotrusion 210 is aligned with the annular groove 236 of the controlsleeve 234, whereupon the bias of the torsion spring 230 will rotate thesupport ring 218 and the clamping collar 202 so that it moves in aclockwise direction to its clamping position shown in FIG. 19. In thisposition, the cam surface 252 has engaged the detente 248 so that itenters the hole 28 of the shank 20. The drawing of FIG. 19 does not showa blade present, which is the reason that the conical portion of thedetente 248 is extended into contact with the opening 208 in which thepin 206 is inserted. Similarly the position shown in FIG. 16 is aclamped position without a blade having been inserted. If a blade wereinserted, the pin 206 would be located approximately midway between theends of the slot 204, the exact position being a function of thethickness of the blade having been inserted.

It should be appreciated that all embodiments of the present inventionare adapted to apply a generally uniform holding force regardless of thethickness of the blade or other tool accessory that is installed in theapparatus. When the control sleeve 234 is pushed rearwardly to releasethe clamping collar, it loads the compression spring 244. Also, thetorsion spring 230 causes the clamping collar and support ring to rotateto the position as shown in FIG. 19 where the blade would be locked inplace. To unclamp the blade, the user merely needs to rotate theclamping collar in the counterclockwise direction as shown in FIGS. 16,18 and 19, which will enable the detente 248 to be released from theblade. When the clamping collar 202 is rotated to a point where theprotrusion 210 is aligned with the axial slot 238, the force of thecompression spring on the control sleeve 234 will push it forwardly andnormally eject the blade 14 from the apparatus.

In the event that the various embodiments of the present invention areinstalled on power tools that experience excessive forces duringoperation, the materials from which the present apparatus are made ispreferably steel or other hard metal, with the exception that the springretainers do not normally experience excessive stresses and thereforemay be fabricated from plastic or plastic-like material.

While various embodiments of the present invention have been shown anddescribed, it should be understood that other modifications,substitutions and alternatives are apparent to one of ordinary skill inthe art. Such modifications, substitutions and alternatives can be madewithout departing from the spirit and scope of the invention, whichshould be determined from the appended claims.

Various features of the invention are set forth in the following claims.

What is claimed is:
 1. A tool-less blade clamping apparatus for a reciprocating tool of the type which has a reciprocating plunger with at least one radially oriented aperture and a blade receiving slot at a forward end for receiving a blade of the type which has a shank portion with a hole and outwardly extending shoulders on opposite sides thereof between a distal end of the shank and a blade portion, the shank being configured to be inserted in the slot, the apparatus being configured to be attached to the plunger and having an opening for receiving the blade shank therein and in the slot, said apparatus comprising: an inner sleeve partially surrounding and axially fixed to the forward end of the plunger; and an outer sleeve positioned concentrically outside the inner sleeve and being axially movable in relation to the inner sleeve and the plunger, wherein the clamping apparatus has a clamped position, in which the blade is securely retained in the clamping apparatus, and an unclamped position, in which the clamping apparatus is configured to receive the blade, wherein, in the unclamped position, the clamping apparatus is locked in position so as to remain in the unclamped position without application of an external force, wherein, during insertion of the blade into the clamping apparatus, the blade shoulders engage the outer sleeve to push the outer sleeve axially in a rearward direction, away from the forward end of the plunger, to release the apparatus from the unclamped position, wherein the clamping apparatus is biased such that, once released from the unclamped position, the clamping apparatus moves to the clamped position to securely retain the blade in the clamping apparatus, and wherein, the outer sleeve is configured to be rotated in a first rotational direction to move the clamping apparatus from the clamped position to the unclamped position, and movement of the apparatus from the clamped position to the unclamped position results in the outer sleeve moving axially in a forward direction to engage the shoulders of the blade and move the blade in the forward direction to eject the blade from the clamping apparatus.
 2. The clamping apparatus of claim 1, further comprising: the outer sleeve defining a circumferentially elongated slot; and a pin fixed to the plunger and extending radially outwardly into the circumferentially elongated slot in the outer sleeve.
 3. The clamping apparatus of claim 2, wherein: the circumferentially elongated slot has a first end and a second end, and the second end of the circumferentially elongated slot includes an extension defined in the outer sleeve extending axially in the rearward direction, and in the unclamped position, the pin rests in the extension of the circumferentially elongated slot to rotationally couple the outer sleeve to the plunger and lock the clamping apparatus in the unclamped position.
 4. The clamping apparatus of claim 3, wherein: during insertion of the blade into the clamping apparatus, the blade shoulders engage the outer sleeve resulting in the outer sleeve moving axially in the rearward direction with respect to the plunger to release the pin from the extension into a circumferential portion of the circumferentially elongated slot, and once the pin is released into the circumferential portion of the circumferentially elongated slot, the outer sleeve is biased to rotate in a second opposite rotational direction until the pin is positioned at the first end of the circumferentially elongated slot, at which point the clamping apparatus is in the clamped position.
 5. The clamping apparatus of claim 4, wherein: the outer sleeve includes a diagonal wall defined in an interior surface of the outer sleeve, the diagonal wall being axially spaced apart from the first end of the circumferentially elongated slot by a first distance and being axially spaced apart from the second end of the circumferentially elongated slot by a second distance, which is greater than the first distance, and the inner sleeve includes a protrusion extending radially outwardly from the inner sleeve to engage the diagonal wall in the outer sleeve, the engagement of the protrusion and the diagonal wall defining a radial and axial position of the outer sleeve relative to the inner sleeve.
 6. The clamping apparatus of claim 5, further comprising: a spring exerting a force on the inner sleeve to bias the protrusion into engagement with the diagonal wall, wherein, once the pin is released into the circumferential portion of the circumferentially elongated slot, the spring urges the protrusion axially against the diagonal wall such that the outer sleeve rotates in the second rotational direction toward the clamped position.
 7. The clamping apparatus of claim 6, wherein rotation of the outer sleeve in the first rotational direction urges the diagonal wall against the protrusion resulting in the outer sleeve moving axially in the forward direction to engage the shoulders of the blade and eject the blade from the clamping apparatus.
 8. The clamping apparatus of claim 4 further comprising: a torsion spring fixed at one end to the plunger and rotationally fixed at an opposite end to the inner sleeve, the torsion spring configured to rotationally bias the inner sleeve in the second rotational direction, wherein the inner sleeve is rotationally fixed to the outer sleeve such that once the pin is released into the circumferential portion of the circumferentially elongated slot, the torsion spring urges the outer sleeve to rotate in the second rotational direction toward the clamped position.
 9. The clamping apparatus of claim 8, further comprising: a compression spring resting against the outer sleeve to bias the outer sleeve axially in the forward direction so that when the outer sleeve is positioned such that the pin is at the second end of the circumferentially elongated slot, the compression spring moves the outer sleeve in the forward direction such that the extension engages the pin and the outer sleeve engages the shoulders of the blade to move the blade in the forward direction to eject the blade from the clamping apparatus.
 10. A tool-less blade clamping apparatus for a reciprocating tool of the type which has a reciprocating plunger with at least one radially oriented aperture and a blade receiving slot at a forward end for receiving a blade of the type which has a shank portion with a hole and outwardly extending shoulders on opposite sides thereof between a distal end of the shank and a blade portion, the shank being configured to be inserted in the slot, the apparatus being configured to be attached to the plunger and having an opening for receiving the blade shank therein and in the slot, said apparatus comprising: an inner sleeve partially surrounding and rotationally fixed to the forward end of the plunger and axially movable in relation to the plunger; and an outer sleeve positioned concentrically outside the inner sleeve; wherein the clamping apparatus has a clamped position, in which the blade is securely retained in the clamping apparatus, and an unclamped position, in which the clamping apparatus is configured to receive the blade, wherein, in the unclamped position, the clamping apparatus is locked in position so as to remain in the unclamped position without application of an external force, wherein, during insertion of the blade into the clamping apparatus, the blade shoulders engage the inner sleeve resulting in the inner sleeve moving axially in a rearward direction with respect to the plunger and the outer sleeve to release the apparatus from the unclamped position, wherein, the clamping apparatus is biased such that once released from the unclamped position, the clamping apparatus moves to the clamped position to securely retain the blade in the clamping apparatus, and wherein the outer sleeve is rotated in a first rotational direction to move the clamping apparatus from the clamped position to the unclamped position, and movement of the apparatus from the clamped position to the unclamped position results in the inner sleeve moving axially in a forward direction to engage the shoulders and move the blade in the forward direction to eject the blade from the clamping apparatus.
 11. The clamping apparatus of claim 10, further comprising: the outer sleeve defining a circumferentially elongated slot; and a pin fixed to the plunger and extending into the circumferentially elongated slot in the outer sleeve.
 12. The clamping apparatus of claim 11, wherein: the inner sleeve defines an annular groove and an axial slot which opens into the annular groove, the outer sleeve includes a protrusion extending inwardly to engage one of the axial slot and the annular groove of the inner sleeve, in the unclamped position, the protrusion engages the axial slot to rotationally couple the inner sleeve and the outer sleeve and lock the clamping apparatus in the unclamped position, and axial movement of the inner sleeve in a rearward direction releases the protrusion from the axial slot into the annular groove, axially fixing the inner sleeve with respect to the outer sleeve and rotationally uncoupling the outer sleeve and the inner sleeve.
 13. The clamping apparatus of claim 12, further comprising: a support ring rotationally fixed to the outer sleeve and positioned in axial engagement with a rear end portion of the outer sleeve; and a torsion spring engaging the support ring such that once the protrusion releases from the axial slot into the annular groove, the torsion spring biases the support ring and the outer sleeve in a second opposite rotational direction until the first end of the circumferentially elongated slot engages the pin and the clamping apparatus is in the clamping position.
 14. The clamping apparatus of claim 13, further comprising: a compression spring configured to bias the support ring and the outer sleeve axially in the forward direction, wherein the axial slot has a first slot end, where the axial slot opens into the annular groove, and a second opposite slot end, and wherein the outer sleeve is configured to be rotated from the clamping position in the first rotational direction until the protrusion is positioned at the first slot end of the axial slot and the pin is positioned at the first end of the circumferentially elongated slot, at which point the compression spring urges the inner sleeve in the forward direction to (i) slide the axial slot past the protrusion until the protrusion is at the second slot end of the axial slot and (ii) engage the inner sleeve with the shoulders of the blade to move the blade in the forward direction and eject the blade from the clamping apparatus. 